EXTINCT ORDERS OF REPTILES. 



217 



the existence in the later Carboniferous period of a gigantic 

 reptile allied to Ichthyosaums. If this view were confirmed, 

 it would carry back the range of the Ichthyosaurs to the 

 Carboniferous ; but it is believed by Huxley that these re- 

 mains may truly belong to some large Labyrinthodont. 



Fig. 566. — Two vertebrae of Eosaurus Amdtensis (Marsh). Coal-measures of Nova Scotia. 

 (After Dawson.) 



As regards their habits, there is no doubt whatever but 

 that the Ichthyosauri were essentially marine animals, and 

 they have been often included with the next order (Sauro- 

 pterygia) in a common group, under the name of Enaliosauria 

 or Sea-lizards. 



In the biconcave vertebrae and probable presence of a ver- 

 tical tail-fin, the Ichthyosaums approaches the true Fishes. 

 There is, however, no doubt as to the fact that the animal 

 was strictly an air-breather, and its reptilian characters can- 

 not be questioned, at the same time that the conformation of 

 the limbs is decidedly Cetacean in many respects. Much 

 has been gathered from various sources as to the habits of the 

 Ichthyosaurus, and its history is one of great interest. From 

 the researches of Buckland, Conybeare, and Owen, the fol- 

 lowing facts appear to be pretty well established : That the 

 Ichthyosauri kept chiefly to open waters may be inferred 

 from their strong and well -developed swimming- apparatus. 

 That they occasionally had recourse to the shore, and crawled 



